git clone https://example.com/your/repo.git git clone git@github.com:user/repo.git Use HTTPS for better firewall compatibility, or SSH if you have keys configured. HTTPS requires authentication via personal access tokens or git credentials; SSH uses key-based auth. List branches # Local branches only git branch # All branches (local and remote) git branch -a # Show branch tracking information…
Git submodules let you keep external repositories as subdirectories within your project while maintaining separate commit histories. They’re useful for managing dependencies, shared libraries, or multi-repo projects—but they require explicit commands to work properly. Adding a Submodule To add a submodule to your repository: git submodule add https://github.com/user/repo.git ./path/to/submodule This creates or updates .gitmodules and…
You often need to access a Git server that only accepts internal connections, but you have SSH access to an intermediate host that can reach it. This is common in corporate environments where the Git server sits behind a firewall. You can tunnel Git traffic through the intermediate host without manually managing tunnels for each…
You’ve got internal hosts on RFC 1918 addresses (10.0.3.0/24, 172.16.0.0/12, etc.) behind a gateway, and you need SSH access to them from your workstation. Traditional solutions involve iptables port forwarding, non-standard ports, and a maintenance nightmare. ProxyCommand offers a cleaner approach: direct SSH connections to internal IPs that actually work. How ProxyCommand Works SSH’s ProxyCommand…
SSH performance is constrained by cipher choice, especially for large file transfers over high-bandwidth links where CPU becomes the bottleneck. Selecting the right cipher, key exchange algorithm, and compression settings can yield substantial throughput improvements. Current Cipher Landscape Modern OpenSSH (7.4+) has deprecated or removed weak ciphers. Here’s what’s viable today: Secure and performant: chacha20-poly1305@openssh.com…
WordPress performance depends on three complementary caching layers: PHP bytecode caching (OPcache), page caching (WP Super Cache), and asset optimization (Autoptimize). Combined properly, they’ll cut your Time to First Byte in half and significantly improve Core Web Vitals. Enable OPcache in PHP OPcache caches compiled PHP bytecode in shared memory, eliminating parse and compile overhead…
Emacs startup is slow. If you’re using it for quick edits alongside other tools, waiting 2-3 seconds every time becomes friction. Heavy mode configurations, lazy loading chains, and initialization hooks add up fast. The server/client architecture solves this: start an Emacs server once, then spawn lightweight clients that connect almost instantly. Your first edit waits…
Benchmarks exist to answer one question: how fast can this system process data? The AMPLab Big Data Benchmark, developed by UC Berkeley, became a foundational effort to answer that question systematically across different distributed query engines. The Benchmark’s Original Scope The AMPLab benchmark evaluated five systems circa 2013: Redshift – Amazon’s columnar data warehouse (built…
Resource management and error handling are critical in systems programming. RAII (Resource Acquisition Is Initialization) originated in C++ and ties resource lifecycles to object scope, with destructors automatically cleaning up resources. C lacks destructors and exceptions, but you can achieve similar semantics using established patterns that are battle-tested in production systems. The goto-based cleanup pattern…
Self-hosting a photo gallery gives you control over your content. If you want to skip database management entirely, a handful of PHP solutions still work—though most are unmaintained. This post covers what’s still functional, where the limits are, and when you should choose something else instead. Static File-Based Gallery Scripts Single File PHP Gallery Status:…
Choosing the right cloud storage service requires understanding how each platform handles data consistency. This post covers the current consistency guarantees from the three major providers and how they affect your application design. Amazon S3 S3 is a key-based object store built for Internet-scale workloads. The consistency model is now straightforward across all operations. S3…
RAID0 (striping) on enterprise RAID controllers like Broadcom MegaRAID is used to expose multiple disks as a single logical volume with no redundancy. This configuration is appropriate only for performance-critical workloads where data loss from a single disk failure is acceptable, or for temporary/cache storage. This guide covers the full setup process on servers with…
The proprietary fglrx driver reached end-of-life in 2015 and is incompatible with current Fedora releases. For modern AMD GPUs, use AMDGPU—AMD’s actively maintained open-source driver that supports Wayland, current kernel versions, and both desktop and compute workloads. GPU Compatibility RDNA and newer (RX 5000 series and later): AMDGPU is required and fully supported. GCN-era Radeons…
Xen remains in production use at scale across AWS EC2, Citrix Hypervisor, and various cloud providers, though KVM has become the default hypervisor for most Linux distributions. If you’re operating a Xen environment, Dom0 resource management is critical to system stability. Why Dom0 Resource Management Matters Dom0 performance directly affects your entire virtualized infrastructure. Since…
This guide sets up OpenLDAP for centralized authentication and NFS with automount to provide unified home directories across a cluster. The setup uses modern OpenLDAP backends and current NFS4 best practices. System Environment Server: LDAP and NFS: 10.0.0.2, Fedora 41 x86_64 Base DN: dc=lgcpu1 Clients: Range: 10.0.0.1/24, Fedora 41 x86_64 LDAP Server Setup Package Installation…
Measuring time accurately matters for performance profiling, benchmarking, and latency-sensitive applications. Linux provides several APIs with different tradeoffs in resolution, overhead, and reliability. Understanding which to use prevents subtle bugs in production code. POSIX Time APIs: gettimeofday and clock_gettime gettimeofday() and clock_gettime() are the standard POSIX calls for reading system time. gettimeofday() returns seconds and…
John Ousterhout, a professor of computer science at Stanford, maintains a collection of “Favorite Sayings” grounded in decades of building real systems—RAMCloud, Tcl, and extensive work in distributed systems. These aren’t abstract principles. They’re lessons that apply directly to the work of building, debugging, and shipping software at scale. Optimize After Measurement, Not Before The…
When /etc/fstab contains errors or your hardware configuration changes, the system may fail to boot or hang during the mount phase. You can recover by modifying kernel parameters at boot time to bypass automatic mounting, then repair the configuration. Method 1: Boot to Single-User Mode Single-user mode skips mounting filesystems listed in fstab, letting you…
The passwd command is designed for interactive use—it prompts for input rather than accepting passwords via stdin by default. When you need to set passwords programmatically (bulk user provisioning, CI/CD automation, remote administration), you need methods that bypass the interactive prompt. Using passwd with –stdin The –stdin flag tells passwd to read the new password…
Ubuntu locks the root account by default as a safety measure—it prevents accidental system damage and enforces audit trails through sudo. If you genuinely need direct root access, here’s how to enable it and the security tradeoffs involved. Set a root password The simplest approach: sudo passwd root You’ll be prompted to enter and confirm…